Central corneal endothelial morphometry in emmetropic adults aged 20-40 years examined in Valencia, Spain: a retrospective cross-sectional analysis.

PURPOSE: To provide a descriptive anatomical baseline for central corneal endothelial morphometry and examine cross-sectional associations with recorded sex and age in emmetropic adults examined in Valencia, Spain. METHODS: This retrospective cross-sectional secondary analysis included 202 de-identified records from adults aged 20-40 years. The historical research program operated from 2002 to 2012; exact participant-level examination dates were unavailable. Emmetropia required a spherical equivalent from -0.50 to +0.50 D, manifest sphere and cylinder within ±0.50 D, and best-corrected visual acuity of 20/20 or better. We obtained endothelial cell density (ECD), coefficient of variation of cell area (CV), percentage of hexagonal cells (%HEX), and mean cell area (MCA) using Topcon SP-2000P non-contact specular microscopy. We used Welch tests, Hedges' g, and false-discovery-rate correction for sex comparisons; age-adjusted models used HC3 robust standard errors with diagnostic and sensitivity analyses. RESULTS: The sample comprised 106 men and 96 women. Overall values were ECD 2908.1 ± 277.5 cells/mm2, CV 32.6 ± 3.7%, %HEX 59.9 ± 6.4%, and MCA 350.2 ± 35.0 µm2. No endpoint showed a detectable sex association after multiplicity control or age adjustment. Age was cross-sectionally associated with lower ECD, larger MCA, and modestly lower %HEX, although the %HEX association attenuated in sensitivity analyses. ECD and MCA were strongly inversely correlated (r = -0.803). CONCLUSION: These device- and sample-specific data provide an anatomical comparator for future studies but are not formal clinical reference intervals or surgical thresholds.